<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    
    var $bus = {
        eventList: {},
        $emit: function (fnName,value) {
          $bus.eventList[fnName](value)
        },
        $on: function(fnName, fn){
          let a = {
            [fnName]: fn
          }
          $bus.eventList = {
            ...$bus.eventList,
            ...a
          }
        }
       
      }


    function request () {
      var xhr = new XMLHttpRequest()
        xhr.open('post', 'http://localhost:3000/list')
        xhr.send()
        xhr.onreadystatechange = function(){
          if (xhr.readyState == 4) {
            let data = JSON.parse(xhr.responseText).data
            // 直接渲染
            $bus.$emit('ok', data)
            
          }
        }
    }


    $bus.$on('ok', (data)=>{
      data.forEach(item => {
        document.body.innerHTML += `<p>${item.name}</p>`
      });
    })
    

    request()

  </script>
</body>
</html>